Well reaming tool



Aug. 22, 1939. J. GRANT WELL REAMING TOOL Filed June 22, 1937 2 Sheets-Sheet 1 INVENTOR Ja/m rw/rf A. u I Q)? s J. GRANT WELL REAMING TOOL Aug. 22, 1939.

Filed June 22, 1937 2 Sheets-Sheet 2 A R H J Wm W m .E

Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates broadly to well drilling and reaming tools and is more particularly directed to the preparation of a well bore to accommodate a formation tester to be subsequently H employed in making a production test.

More specifically the present invention contemplates the drilling of a rat-hole extending downwardly from the well bore proper and having a packer seat of suitable contour and length and so disposed as to accommodate the usual types of formation testers by means of which production tests are made, it being an important object of the invention to make provisions for forming such seat by means associated with the rat-hole drilling string and under control of the operator at the well surface whereby the seat may be formed at will before withdrawal of said stri and while the rat-hole drilling bit remains in the drilled rat-hole to serve as a pilot guide for the seat forming means. Another important object is to render the seat forming means operative by restricting the flow of circulation fluid and utilizing the power incident to such restriction to expand said seat forming means, a further object being to utilize a flow restricting means of the go-devil type adapted to be sent down the bore of the drill string to function as an actuator for the seat forming means.

The means enabling the practice of the above defined method, the provision of which means is a further important object of the present invention, includes a normally collapsed expansible reamer adapted to be incorporated in the rathole drill string above the rat-hole drilling bit and provided with reaming cutters and a cutter expanding means which is normally inactive but is arranged to be actuated at Will by an actuator of the go-devil type sent down the bore of the drill string by the operator. Another object is to provide an actuator of the go-devil type which "may be elevated from its reamer actuating position by means lowered into the drill string by a part of this disclosure, and which illustrate a preferred embodiment of the invention.

Of the drawings: 7

Fig. 1 is a vertical section through the lower end portion of a well bore and rat-hole showing 5 the rat-hole drilling string in drilling position with the seat forming reamer in its normal collapsed condition, there being also shown in dotted lines a well bore reamer which may, if desired, be incorporated in the rat-hole drill string and uti- 1o lized to deepen the well bore as the rat-hole is being drilled.

Fig. 2 is a similar vertical section showing the rat-hole drilling string elevated to position the, seat reamer above the rat-hole shoulder and showing the'seat reaming blades or cutters thereof expanded to their seat reaming position.

Fig. 3 is a similar vertical section showing the rat-hole drilling string in its seat reaming position.

Fig. 4 is a vertical section showing the finished seated rat-hole with a formation tester in operative position, the drilling string having been withdrawn from the well bore and such formation tester having been lowered to place by a string of rotary pipe extending to the well surface.

Fig. 5 is a vertical section through the expansible reamer, in its normal collapsed condition, showing the actuating go-devil on its way down to its reamer expanding position.

' Fig. 6 is a similar section showing the go-devil at the lower limit of its travel and the; reamer mechanism in expanded condition, this sectional view also showing a go-devil grab whichmay, if desired, be lowered through the drill stringby a sand line or the like to engage and elevate the go-devil to permit collapse of the reamer.

Fig. '7 is a transverse section taken on the line 1--'| of Fig. 5.

Fig. 8, is a transverse section taken onthe line 8-8 of Fig. 5.

Fig. 9 is a transverse section taken on the line 99 of Fi 5.

Fig. 10 is a transverse section taken on the line Ill-l0 of Fig. 6.

Figs. 11 and 12 are vertical sections illustrating two respective modified forms of cutter expanding means. 1

Rat-hole testing for determining the productivity of sands encountered in the drilling of a well bore is Widely practiced in the several oil fields and is recognized as a safe and economic procedure since it enables promising sands occurring at any depths to be readily tested without the necessity of bailing the well bore, with the resulting danger of cave-ins, and without requiring the setting of easing which, besides entailing considerable expense and delay, would unnecessarily reduce the size of the well bore, the setting of a casing for each production test being further undesirable since such proceedure may either reduce the size of the well bore to a prohibitive degree, or limit the number of tests that may be made in a given well with the result that sands which might have been commercially productive would be passed by.

A production tester, of which there are several known makes now in general use, may be generally described as comprising a tubular body which is attached to the lower end of a string of drill pipe and which has an interior valve normally closed to prevent entrance of fluid, said body being provided with an external packer, preferably of cone form to seat in the mouth of the rat-hole to provide a shut-off preventing the circulation fluid in the well bore proper from flowing into the rat-hole during the taking of the production test. The tester is provided with a perforated pipe or other sand excluding means depending into the rat-hole. Various arrangements may be provided for opening the inlet valve after the tester is seated, the valve of the standard form of tester herein illustrated being opened or closed by rotation of the drill pipe which has a swivel connection with the tester body.

Heretofore, the procedure in rat-hole testing has been as follows. First, a drill string provided with a rat-hole drilling bit is lowered into the Well bore and rotated to drill the rat-hole, second, the rat-hole being drilled to the desired depth beyond the well bore proper, this drill string is withdrawn from the well and a nonexpansible mill or reamer is substituted for the rat-hole bit, third, the drill string is again lowered into the well and rotated to cut or ream the rat-hole shoulder to form a tapered seat, fourth, the drill string is again withdrawn from the 'well and the formation tester attached thereto in place of the reamer, fifth, the drill pipe then lowers the formation tester into the well to engage the rathole seat, after which the tester inlet valve will be opened to allow the fluid, if any, in the tested sand, to enter the rat-hole and flow through the tester valve and into the drill pipe, subsequently the tester valve will be closed and the drill pipe and tester withdrawn from the well to recover the test fluid. three complete round trips of the drill string or pipe, each trip involving considerable expense and requiring two or more hours in well bores of average depth.

The present invention is not primarily directed to the formation tester or to the making-of production tests but more specifically involves a method and means by which, in a single round trip of the drill string, the rat-hole is drilled and reamed to provide a suitable seat for accommodating a formation tester to be subsequently employed for making a production test. Thus the seated rat-hole is completed in one-half the time and at one-half the labor expense involved in the prior methods which require one round trip of the drill string for drilling the rat-hole and a second round trip thereof for reaming the tester seat therein.

As illustrated in Figs. 1 to 4 of the drawings, designates the well bore proper which extends through various formations to the surface and This usual procedure requires ll designates the rat-hole which extends dow'n wardly from the bottom of the well bore through a cap structure and into a known or suspected oil sand. The forming of such rat-hole by the method herein disclosed involves the drilling of said rat-hole with a rat-hole drilling bit l2 carried by a rotary drill string which includes a normally collapsed expansible reamer l3 (see Fig. 1) and a rotary drill pipe l4 which extends to the usual rotary driving table at the well surface. When said rat-hole II has been drilled to a desired depth into the sand structure the drill string is elevated sufiiciently to position the reamer 53 above the rat-hole shoulder Ill and is there ex panded, as shown in Fig. 2. With said reamer expanded, the drill string is rotated and fed downwardly to enable the expanded reaming cutters to ream or chamfer the rat-hole shoulder l4 and form a tapered seat 15 at the mouth of the rat-hole, as shown in Fig. 3. Upon completion of the seated rat-hole, the drill string is withdrawn from the well bore and the reamer and rat-hole bit detached therefrom to be replaced by a formation tester. Any one of the several well known types of formation testers may be employed in making a production test, the tester illustrated being a more or less popular type which comprises a tubular body i5 communicating with the bore of the drill pipe l4 and with a depending perforated inlet pipe 31 and having an internal normally closed inlet valve (not shown) and an external cone packer I8 of rubber or other suitable material. The inlet valve is opened and closed by rotation of the drill pipe and the body it of said tester is swiveled thereto to permit the drill pipe to rotate relative to said body.

In making a production test the tester is lowered into the well bore until its cone packer l8 seats in the rat-hole seat l5 to secure a shutoff between the well bore i0 and the rat-hole H and the inlet valvethereof is then opened to permit such oil as the sand structure may contain to flow into the tester and up. the drill pipe. After a suitable interval the inlet valve will be closed and the tester removed from the well bore to recover the test fluid.

Quite obviously this method or the type of reamer employed is in no Way afiected by the particular type of bit used to drill the rat-hole therefore the term rat-hole drilling bit as herein employed is intended to include any type of bit or drill which will bore a rat-hole of the proper size and depth and also to include coredrills which may be used to take a core of the sand structure during the drilling of the rat-hole. In dotted lines in Fig. 1, there is indicated a well bore reamer which may be employed to deepen the well bore proper as the rat-hole is being drilled in advance thereof until a prospective oil sand is reached, after which the procedure will follow the method of the present invention.

While this method may be carried into efiect by the utilization of expansible reamers of different types, it is preferred to employ a. reamer of the character illustrated in Figs. 5 to 12 of the drawings.

Referring to Fig. 1 which shows the reamer in its normal collapsed condition, 2!] designates the tubular body of the reamer, which body has a lower end screw-threaded to receive a lower sub 2| to which the rat-hole bit i2 is connected by the usual pin and box connection, and an upper end similarly screw threaded to receive an upper sub 22 to which the drill collar 23 of the drill'pipe the circulation fluid will maintain these packis connected, also by the usual pin and box connection.

The bore of the body has a medial portion of relatively small diameter and is enlarged at opposite ends to provide an upper cylinder or mandrel chamber 24 and a lower cylinder or spring chamber 25. A cutter expanding mandrel is slidable within the bore of the body and comprises a mandrel head 26 disposed in the mandrel chamber 24, a mandrel bushing 21 disposed within the spring chamber 25, and a connecting mandrel tube 28 slidable through the medial portion of the bore and connecting the mandrel head and bushing so that they slide within the body bore as a unit. A coil spring 29 within the spring chamber rests on the lower sub 2| with its upper end bearing against the mandrel bushing 21. This spring yieldingly maintains the mandrel assembly in its uppermost position with its bushing 21 contacting the stop abutment 30 formed by the upper wall of the spring chamber 25. The cylindrical mandrel head 26 has a downwardly and inwardly converging tapered portion 3| and a closely adjacent end which tapers downwardly and inwardly at a more abrupt angle to forma cutter expanding shoulder 32. The specific reamer illustrated is provided with three circularly spaced reaming cutters, and although it will be evident that a greater or less number of cutters may be employed and that cutters of other forms may be used, it is preferable to provide three reaming cutters 33 of the blade type disposed within companion slots formed in the wall of the body 20 tointersect the bore thereof. Each cutter 33 is pivoted at its lower end on a transverse pin 34 and has secured to its inner lower wall portion a leaf spring 35, the free end of which engages the lower wall of the cutter slot. Such spring, which extends part way around the pivotal center of the cutter blade, serves to urge said blade to collapsed position. The upper inner end portion of each cutter blade is beveled to normally engage under the angled shoulder 32 of the mandrel head 26 and is provided with opposite retaining wings 36 which are normally disposed within the lower end of the mandrel chamber 24 between the mandrel tube 28 and the inner wall surface of the body, as shown in Fig. 8. Although the mandrel tube 28 could be made integral with either the mandrel head 26 or with the mandrel bushing 21 itis,

in order to effect certain economies in manufacture and to facilitate assembling, preferable to weld the upper end of the mandrel tube 28 to the mandrel head 26, as indicated at 31, insert these joined parts into the body from the upper end of its bore, and then insert the mandrel bushing 21 into the spring chamber 25 and press it onto the lower end of the mandrel tube 28 with a drive fit.

.To prevent escape of circulation fluid the mandrel head 26 and the mandrel bushing 21 are provided with packing rings 38 and 39 disposed in companion grooves cut in the peripheral walls of the respective parts. These packing rings are preferably of rubber and communicating ports 40, 4| are provided, in the mandrel assembly leading from the circulation passage, formed by the bore of the mandrel tube, to each respective packing groove so that the pressure of ing rings expanded against the inner wall of the reamer body. The mandrel bushing 21 has an added channel 42 surrounding the mandrel tube since it would be diificult to align the two portions of its communicating ports prior to driving said bushing on the end of the mandrel tube. This mandrel arrangement in fact constitutes what may aptly be termed a cutter expanding piston, the upper mandrel head 26 functioning as anupper piston slidable in the upper chamber or cylinder 24 and the mandrel bushing 21 functioning as a lower piston slidable in the lower spring chamber or cylinder 25, these two pistons being joined together by the mandrel tube 28 which serves as a hollow piston rod.

Slidable in the body bore above the mandrel head 26 and operating in unison therewith is a tubular seat member 43 which is provided with three stop lugs 44 projecting inwardly into its bore. As will be explained in connection with the modified forms shown in Figs. 11 and 12, this member 43 may be mounted directly in the mandrel head or be an integral portion of said member without in any way changing its purpose or function since the object in making it a separate piece is to enable it to be reversed end-forend in event one end becomes unduly worn.

This reamer is adapted to be expanded at will by means under control of the operator at the well surface and the preferable means which is employed for this purpose is one which may be sent down the drill string bore to restrict the normal free flow of the circulation fluid through the reamer and permit utilization of the power incident to such flow restriction for operating the cutter expanding mandrel. Such means may aptly be termed an actuator go-devil and in its preferred form comprises a tubular member 45 of such diameter as to freely slide down the bore of the drill pipe to engage the reamer mandrel and having a bore of such size as to adequately diminish the circulation passage of the mandrel and restrict the flow of the circulation fluid therethrough. This actuator go-devil 45 has duplicate ends so it may be sent down the drill pipe either end first and is provided with packing rings 43 and 47 similar in nature and function to the packing rings 38 and 39 of the mandrel assembly and serving to prevent flow of the circulation fluid around the go-devil when it is seated in the mandrel assembly against the stop lugs 44 of the seat member 43. Further, there is provided transverse ports 48 allowing circulation fluid to flow from the bore of the .go-devil into the space between the upper sub 22 and the stop member 43 so as to exert downward pressure on the mandrel assembly. For a purpose to be later described said go-devil is provided with a series of relatively spaced internal grooves 49. Since the. mandrel head 26 and mandrel bushing 2? which function as upper and lower piston elements, have approximately equal areas exposed to the pressure of the circulation ifluid, the mandrel assembly will normally be substantially counterbalanced as to fluid pressures and the coil spring 23 will support the mandrel in its elevated position, as in Fig. 5. The reamer will remain in this collapsed condition until the actuator go-devil 45 reaches the reamer and engages against the stop lugs 44 to appreciably restrict the flow of fluid into the mandrel bore and thus materially reduce the pressure below said mandrel, while at the same time a portion of said fluid passing through the transverse ports 48 and into the body bore above the mandrel assembly will exert its predominating pressure on the seat member 43 to overcome the tension of the coil spring 29 and drive the cutter expanding mandrel downwardly so that its tapered surfaces will eifect an expansion of the cutters to the position shown in Fig. 6.

If at any time it becomes necessary, due to accident or desire, to restore the reamer to collapsed condition before withdrawing it from the well bore and while circulation is still being maintained, this may be accomplished by sending down the drill string bore on a sand line, a grab device, one form of such grab device being illustrated in Fig. 6 and being provided with barbed spring arms 56 which will enter the bore of the go-devil to hook in one of the series of grooves is so that the go-devil may be elevated by the sand line to disengage the mandrel assembly and permit equalization of pressure on opposite ends thereof, whereupon, the coil spring 23 will again become effective to elevate the mandrel and permit the cutters to be collapsed by their respective leaf springs 35.

In Fig. 11 there is illustrated a modified structure which permits a greater degree of cutter expansion. In this arrangement the cutter slots are extended upwardly as at to accommodate cutter expanding Wedge blocks 52 which are secured to the mandrel head 52, by screws 53, or by any other suitable means. In this arrangement the several cutter blades have extended heel portions 5% which limit the outward swing of said blades. This view also illustrates a reversible seat member 55, comparable in kind and function to the previously described seat member 13, this seat member being mounted in the mandrel head 52 instead of in the body bore as is the member =33 in the construction illustrated in Fig. 5.

Fig. 12 shows another modified form in which a separate seat member is eliminated, the stop lugs 56 being preferably pressed inwardly from the wall of the mandrel tube 5? and the go-devil seating directly within the upper end of said tube. In either of the three forms shown, the go-devil functions as a valve and the seat members shown in Figs. 5, 6, and 11 and the upper end of the mandrel tube of Fig. 12 function as valve seats, these arrangements providing a valve means for restricting the flow of circulation fim'd through the reamer, In Fig. 12 there is also shown a modified form of cutter expanding means which includes toggle links 58 each pivotally connected to the mandrel head 59 by a pin 8i] and to the respective cutter blade by a pin 6i. In the normal collapsed condition of the reamer, with the mandrel assembly in elevated position, each toggle link 58 will assume a more or less vertical position with its connecting pin 5i) slightly off-center outwardly from an imaginary line intersecting the connecting pin 5! and the pivot pin 34 of the cutter, so that, when the mandrel assembly is forced downwardly the several toggle links 58 will assume the horizontal position shown in Fig. 12, to expand the reamer blades, the lower end portion of the mandrel head 58 contacting the inner upper edge of each blade, as at 62 to provide an abutment relieving the link pins Bil and 6! of the strain of inward thrusts.

In either of these three specific embodiments or in other embodiments of a reamer of character herein disclosed, in which a flow restricting means is employed to unbalance the fluid pressure counterbalance of the mandrel or actuating element, it is of importance that the normal fluid flow through the mandrel assembly and the dego-devil be calculated with specific reference to the volume of discharge of the circulation fluid from the drilling bit with which the reamer is associated. Obviously, in order to build up a back pressure in the lower cylinder or chamber 25 sufficient to effect a pressure counterbalance of the mandrel assembly it is necessary that the bore or flow passage through said mandrel assembly have a volumetric flow capacity which is appreciably greater than the combined flow capacity of all of the discharge orifices 65 of the bit l2, and, since the cutter expanding actuation of the mandrel assembly is effected by an unbalancing of this fluid pressure counterbalance it becomes necessary that the actuator go-devil be capable of so diminishing or restricting the mandrel bore that its changed volumetric flow capacity will be less than that of said drill bit discharge orifices in order to prevent creation of any back pressure in said lower cylinder or chamber. Therefore, in a reamer of this nature the cross-sectional area of the fiow passage or bore through the mandrel assembly should be greater than the combined cross-sectional area of all of the discharge orifices of the bit while the cross-sectional area of the flow passage or bore of the actuator go-devil should be less than that of said discharge orifices.

In the herein defined method of forming a seated rat-hole, the particular advantage incident to the maintaining of the reamer in collapsed condition during the drilling of the rathole and until the tester seat is to, be formed, is that by so doing the reamer cutters are kept in their original sharp condition until actually used to cut the seat, and since it requires sharp reamer cutters to form. a seat in which a formation tester may readily secure a tight fluid shutoff, it will be evident to those skilled in this art that there is a distinct advantage in thus relieving the reamer cutters of wear during the drilling of the rat-hole which may extend to a considerable depth before the tester seat is formed, and while the reamer employed may be provided with various specific forms of cutters to meet varying conditions incident to formations of different characters, it has been found that a blade typeof cutter of the type illustrated herein will cut a seat having a smooth concentric wall which contributes greatly to the securing of a proper shut-off with the usual types of formation testers.

From the foregoing it will be evident that the invention provides a method of forming a seated rat-hole in a Well bore during a single round trip of the drill string and a means fully capable of carrying said method into effect. a

I claim:

1. A well tool which comprises a drill string having a drilling bit at its lower end and having a circulation passage adapted to convey circulation fiuid under pressure to the bit, said drill string including a normally collapsed reamer having an expansible cutter and a relatively movable cutter expanding assembly provided with a flow passage having a normal flow capacity greater than that of the smallest part of said circulation passage and operable by the pressure of said circulation fluid to expand said cutter, and means for restricting the effective fiow capacity of said flow passage to less than that of the smallest part of. said circulation passage and eifect translation of the cutter expanding assembly to expand said cutter.

2. In an expansible reamer, the combination of: a tubular bodyadapted for incorporation in a rotary drill string conveying circulation fluid under pressure to said reamer, a reaming cutter mounted in said body; a cutter expanding assembly slidable in said body to expand said cutter, said assembly having a flow passage whereby its opposite ends are normally equally subjected to the pressure of said circulation fluid; and means adapted to be dropped through the drill string into said body for restricting said flow passage to a greater degree than its normal minimum cross sectional area, said means thereby causing a reduction of the pressure exerted by said fluid on one end of said assembly in relation to that exerted on the opposite end thereof to permit the then predominating fluid pressure exerted on said opposite end to effect translation of said assembly to expand said cutter.

3. In an expansible reamer, the combination of a tubular body adapted for incorporation in a rotary drill string conveying circulation fluid under pressure to said reamer, a reaming cutter mounted in the body; a cutter expanding assembly slidable in said body to expand said cutter and having an upper surface subjected to the pressure of the circulation fluid, said assembly being provided with a fluid passage for entraining the circulation fluid to an under surface thereof of equal area whereby said assembly is normally counterbalanced as to fluid pressures; and valve means adapted to be sent down the drill string bore from the well surface and functioning to restrict said fluid passage to disturb said pressure counterbalance and cause said assembly to be translated to cutter expanding position by the then predominating fluid pressure exerted on its upper surface.

4. A well reaming tool comprising a body adapted to be attached to a drill string and containing a passage through which circulating fluid is discharged from the drill string, an expansib-le cutter carried by the body, cutter expanding means operable by the fluid pressure, and a go-devil adapted to be sent down through the drill string into said body and into engagement with the cutter expanding means, said go-devil containing a fluid duct of smaller cross sectional area than the minimum cross sectional area of said passage, and thereby producing an increase of the fluid pressure applied to said expanding means to cause it to expand the cutter.

5. A well reaming tool comprising a body adapted to be attached to a drill string, an exwardly through the drill string into operative association with said passage and to restrict the passage to a greater degree than its minimum cross sectional area, thereby increasing the fluid pressure applied to the member and causing the member to expand the cutter.

6. A well reaming tool comprising a body adapted to be attached to a drill string, an expansible cutter carried by the body, a cutter expanding member movable vertically within the body by fluid pressure and containing a passage through which fluid is discharged from said drill string, and a go-devil adapted to be sent down,- wardly through the drill string to seating position in which the go-devil engages the member and extends upwardly within a bore in the body above the member, said go-devil containing a fluid duct of smaller cross'sectional area than the minimum cross sectional area of said passage, so as to increase the fluid pressure applied to the member and thereby cause the member to expand the cutter.

7. A well reaming tool comprising a body having a fluid passage bore and adapted to be attached to a drill string, a cutter expanding member movable vertically within the body by fluid pressure, containing a longitudinal passage through which fluid is freely discharged from the drill string, and having upper and lower end siu'faces exposed to fluid pressure; and a godevil adapted to be sent downwardly through the drill string to a seating position in which the godevil seats on said member and extends upwardly into the fluid passage bore in the body above said member, said go-devil containing a longitudinal fluid duct of smaller cross-sectional area than the minimum cross-sectional area of saidv passage, and containing also a lateral passage leading from its longitudinal passage at a point above the upper end of said cutter expanding member to apply fluid pressure from the restricted longitudinal duct to the upper end of said member, the upper end of the go-devil in the body bore being subject to fluid pressure acting to move the go-devil and said member downwardly.

JOHN GRANT. 

